Leaders Scunthorpe were pegged back by an injury-time equaliser from Jack Sampson at Morecambe which denied them the chance to stretch the gap at the top to four points.
The Iron had looked set to make the most of a tough afternoon for their closest rivals when Sam Winnall put them in front after 22 minutes at the Globe Arena - but Sampson had other ideas.
Second-placed Chesterfield failed to capitalise and could count themselves fortunate to emerge with a point in a 1-1 draw with struggling Exeter.
Matt Grimes put the visitors in front on 18 minutes and things looked bleak for the Spireites when Sam Morsy was red-carded on 75 minutes for a foul on Grimes.
But three minutes later Eoin Doyle salvaged what could prove to be a crucial point for the home side when he tucked away a penalty after being fouled by Danny Butterfield.
Third-placed Rochdale endured an afternoon to forget as they were hammered 3-0 at home by play-off hopefuls Southend.
Barry Corr and Jacob Murphy scored in the first half for the Shrimpers and Michael Timlin also netted one minute after the break to keep his side secure in sixth place.
Fourth-placed Fleetwood were the biggest beneficiaries of the top clubs' jitters as their 2-1 win at Cheltenham moved them to within three points of the top three.
Veteran Jamie Cureton put Cheltenham in front just past the half-hour but the visitors showed plenty of character to fight back through Antoni Sarcevic's 55th-minute penalty and a winner from Josh Morris 10 minutes later.
York swapped places with Oxford in the play-off zone after a superb 1-0 win at the Kassam Stadium, Michael Coulson scoring the only goal of the game with a 48th-minute penalty after Joshua Ruffels' handball.
At the bottom, Torquay look all but doomed after Medy Elito's 67th-minute penalty gave Dagenham & Redbridge a 1-0 win at Plainmoor and left the hosts eight points off safety.
Meanwhile just above them Wycombe and Northampton remain locked together on 47 points after neither side could take full advantage of a nervy 1-1 draw at Adams Park.
Home keeper Matt Ingram served up a horrendous blunder to put through his own goal in the 12th minute but his blushes were spared by Aaron Pierre's equaliser six minutes later.
Daniel Nardiello scored twice as Bury cruised to a 4-0 win over Plymouth with further goals coming from Andrew Tutte and Danny Rose, while Kai Naismith's penalty deep into injury time salvaged a 1-1 draw for Accrington at home to Mansfield, who had led through substitute Jake Speight.
Wimbledon came back from two goals down to draw 2-2 at home to Newport. Chris Zebroski and Michael Flynn got the visitors off to a flyer but Kwesi Appiah and George Francomb grabbed the Londoners a point.
Bradford all but secured their League One future with a narrow but deserved 1-0 win over sixth-placed Peterborough.
The winning goal after 27 minutes was superb 25-yard free-kick from Adam Reach, which went into the net off the inside of the upright.